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Berps Developer Guides: Using Pyth Prices ​

Pyth exposes a number of methods for retrieving pricing data. This page demonstrates a few options for doing so, but is not exhaustive. See Pyth's documentation for the full list.

REST API ​

Hermes is a web service subscribed to the Pyth Network for price updates, and serves them via REST API. The following command retrieves the latest price updates for BTC/USD and ETH/USD:

bash
curl -X 'GET' \
  'https://hermes.pyth.network/v2/updates/price/latest?ids%5B%5D=0xe62df6c8b4a85fe1a67db44dc12de5db330f7ac66b72dc658afedf0f4a415b43&ids%5B%5D=0xc96458d393fe9deb7a7d63a0ac41e2898a67a7750dbd166673279e06c868df0a'

TypeScript SDK ​

Pyth provides a TypeScript SDK for fetching price updates. More information on the SDK can be found here.

First, install the Pyth SDK:

bash
npm install @pythnetwork/pyth-evm-js

Fetch Prices ​

Using the SDK, price updates can be fetched using getLatestPriceFeeds as follows:

typescript
import { EvmPriceServiceConnection } from "@pythnetwork/pyth-evm-js";

const pythConnection = new EvmPriceServiceConnection(
  "https://hermes.pyth.network"
);

const priceIds = [
  "0xe62df6c8b4a85fe1a67db44dc12de5db330f7ac66b72dc658afedf0f4a415b43", // BTC/USD price id
  "0xff61491a931112ddf1bd8147cd1b641375f79f5825126d665480874634fd0ace", // ETH/USD price id
];

const prices = await pythConnection.getLatestPriceFeeds(priceIds);

Get Signed Price Update & Open Trade ​

Berps trading actions expect a signed price update to refresh its internal state. The following code snippet demonstrates how to fetch and submit a signed price update when opening a trade on Berps.

In order to prepare the necessary data for the trade, we first call the Pyth SDK's getPriceFeedsUpdateData to obtain the price update data. Next, getUpdateFee is called to obtain the fee required to update the price feed on-chain.

typescript
import { ethers } from "ethers";
import { EvmPriceServiceConnection } from "@pythnetwork/pyth-evm-js";
import PythAbi from "@pythnetwork/pyth-sdk-solidity/abis/IPyth.json" assert { type: "json" };

// Berachain Artio
const contractAddress = "0x8D254a21b3C86D32F7179855531CE99164721933";
const provider = ethers.getDefaultProvider("https://bartio.rpc.berachain.com/");
const pythContract = new ethers.Contract(contractAddress, PythAbi, provider);

const pythConnection = new EvmPriceServiceConnection(
  "https://hermes.pyth.network"
);

const priceIds = [
  "0xff61491a931112ddf1bd8147cd1b641375f79f5825126d665480874634fd0ace", // ETH/USD price id
  "0xeaa020c61cc479712813461ce153894a96a6c00b21ed0cfc2798d1f9a9e9c94a", // USDC/USD price id
];

const priceUpdateData = pythConnection.getPriceFeedsUpdateData(priceIds);
const updateFee = await pythContract.getUpdateFee(priceUpdateData);

// Use priceUpdates to `openTrade` in Berps:
const tx = await tradingContract.openTrade(
  trade,
  orderType,
  slippage,
  priceUpdateData,
  { value: updateFee }
);

Additional Resources ​

There is a small fee required to update Pyth's on-chain prices. Documentation on the getUpdateFee method is further described in Pyth's docs.

The openTrade call here assumes that the user is opening a trade on the ETH/USD pair, and so price updates to both ETH and USDC price feeds are required (since collateral is denominated in USDC). See the Open Trade guide for more information on the required trading input parameters.